1. Field of the Invention
This invention relates to a method and a device for manufacturing semiconductors. More particularly, the present invention relates to a method and a device for manufacturing spherical semiconductor crystals.
2. Description of the Prior Art
Conventionally, spherical semiconductor crystals are manufactured by buoying small pieces of semiconductor material with the aid of electromagnetic floating coils and at the same time heating them to obtain liquid drops. The liquid drops are solidified during free fall, and spherical semiconductor crystals are thus obtained. A method for manufacturing spherical semiconductor crystals has been disclosed in U.S. Pat. No. 4,322,379. In this patent, bar-shaped or scrap material for producing spherical semiconductor crystals is fed into a quartz tube that is provided with a nozzle at its distal end. After the bar-shaped or scrap material is melted through a coil-heating process, liquid drops are forced to drop down from the distal end of the nozzle by applying a gas pressure. Then, the liquid drops are solidified during free fall, and spherical semiconductor crystals are thus obtained.
However, the following problems remain unsolved in the above-described methods. In the process of buoying and heating small pieces of semiconductor material, a plurality of small pieces of semiconductor material are supplied into a region above the electromagnetic floating coils for heating. However, this process still takes too much time to produce spherical semiconductor crystals. Moreover, the quartz tube employed in the '379 patent deteriorates after several operations. This will cause a hindrance to uninterrupted production of spherical semiconductor crystals. Furthermore, under this process it is required to heat the quartz tube so as to melt the material. The above heating process will fuse the quartz tube and impurities contained in quartz will blend into the liquid drops. Therefore, it is quite difficult to maintain the purity of the produced semiconductor crystals.